Pete is a social worker for the Department of Family Services, working in Tenmile, Montana, at the beginning of the 1980s. He encounters a variety of cases, but none which are so intriguing as the Pearl family. When young Benjamin Pearl wanders into town, half-starved and suffering from vitamin deficiencies, Pete makes it his mission to find out everything he can about the family, even though Ben's father, Jeremiah, warns him that he'll kill him before he lets him have his son. Pete learns that the Pearls have been living in the wilderness for years after Pearl's wife, Sarah, had a vision of an apocalypse ending the world. Since then, Jeremiah has been waging a secret war on the government by defacing coins and redistributing them into the system. Pete is warned that the Pearls are highly dangerous, but he continues to take them supplies. Jeremiah eventually begins to let down his guard around Pete, who in turn bonds with Ben. The other family members are mentioned but never seen; Jeremiah indicates that they are hiding in the woods and that he doesn't trust Pete enough to meet them.

In the meantime, Pete deals with other personal issues. His brother, Luke, is on the run from the law, and his parole officer, Wes, is trying to pester Pete into revealing his location, even going so far as to burn down his house as a warning. Pete is estranged from his wife, Beth, after discovering that she was cheating on him; he has also essentially abandoned his daughter, Rachel, who has always feared her father cared more about his cases than her. This certainly seems to be the case, with Pete continuously choosing to devote his life to help other children but having almost no time for her. Rachel begins experimenting with drinking, partying, and boys, and soon runs away from home. This is the wake-up call that Pete needs, and he devotes his time to trying to find her, though Rachel does not want to be found and constantly evades him. She gets involved with a variety of lowlife characters, finally ending up with a pimp named Pomeroy who leads her into a life of prostitution.

Unable to find Rachel, Pete returns to Tenmile and the Pearls. Just as they are beginning to trust him, Wes follows Pete to the Pearls' camp, believing that Pete has been going to visit Luke. Thinking that Pete has betrayed them to the authorities, Jeremiah and Ben threaten Wes and Pete. Ben shoots and kills Wes. Pete has no choice but to tell the authorities what has happened, and he learns the government has been searching for Jeremiah for quite some time. They also uncover the Pearls' hidden camp, where they find the bodies of Jeremiah's wife and other children. Jeremiah and Ben have gone missing, but their disappearance causes riots in the town, where people begin threatening local authorities and blowing up post offices.

Pete learns that Rachel has been spotted in Seattle and goes to track her down. There, it becomes clear that the social workers and police force are at least partially complicit in allowing teenage girls like Rachel to become prostitutes. Rachel tries to leave, but Pomeroy threatens her, so she arranges for some rival pimps to take him out. In the fray, Pete sees Rachel, but she runs away, unable to face him or herself. Pete reluctantly lets her go, hoping that someday she will come back to him.

Pete returns to Tenmile to learn that Ben has been found. He tells Pete the truth about Sarah and the other children: they became sick and Jeremiah tried to go for help, but Sarah had gone mad with the illness and killed herself and the other children instead. Jeremiah and Ben have been on their own ever since. Pete convinces the authorities to release Ben to foster care. Jeremiah comes looking for Ben, and Pete helps them run off together.